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Re: Remove word_mode hack for split bitfields
- From: Bernd Schmidt <bschmidt at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org, richard dot sandiford at arm dot com
- Date: Tue, 31 May 2016 12:28:32 +0200
- Subject: Re: Remove word_mode hack for split bitfields
- Authentication-results: sourceware.org; auth=none
- References: <8760u0evj5 dot fsf at e105548-lin dot cambridge dot arm dot com>
On 05/26/2016 04:36 PM, Richard Sandiford wrote:
This patch is effectively reverting a change from 1994. The reason
I think it's a hack is that store_bit_field_1 is creating a subreg
reference to one word of a field even though it has already proven that
the field spills into the following word. We then rely on the special
SUBREG handling in store_split_bit_field to ignore the extent of op0 and
look inside the SUBREG_REG regardless. I don't see any reason why we can't
pass the original op0 to store_split_bit_field instead.
Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install?
Any observable effects on code generation?
Bernd